Inductor



June 3, 1930. .R DAVIS ET AL 1,760,975

INDUCTOR Filed April 29, 1927 7 lc; I 7 6 7 6 WITNESSES: lNvENToRSf Robe/f L. Day/LY 3 @d John E? Sra/(el.

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Patented June 3, 1930 NUNITED *srArEs PATENT;y OFFICE ROBERT L. DAVIS, 0F PTTSBURGIEI, AND JOHN P. STAKEL, 0F EDGEWOOD, PENNSYL- VANIA, ASSGNOR-S TO WESTINGHGUSE ELECTRIC AND MANUFACTURING COM- PANY, A CORPORATON OF PENNSYLVANIA INDUCTOR Application filed April 29,

Our invention relates to inductors and particularly to inductors suitable for use with radio-frequency apparatus such as radio transmitting systems, radio-frequency amplifying systems and the like. A

An object of our invention is to provide improved inductance devices in which the energy losses are a minimum,

Another object of our invention is to produce an inductance device adapted for the ready dissipation of heat produced therein byenergy losses.

Another object of our invention is to produce a highly insulated loW-lossinductance device particularly adapted for use in apparatus handling alternating currents at frequencies above 1,000 kilocycles.

Another object of our invention is to pro` vide an inductance device which shall be c`apable of being quickly modified to accommodate either ribbon-like conductors or conductors having substantially circular crosssection.

Another object of our invention is to provide an inductance device capable of carrying large currents at high-voltage radiofrequencies.

A still further and' more specic object of our invention is to provide, for use in connection With an inductance device, conductorsupporting elements that may be ,Y easily adapted for inductors having Widely differing inductance values.

In the construction of inductance devices adapted to be used in apparatus which is arranged to handle currents at radio frequencies, numerous ditliculties have previously been experienced. The energy losses caused by electrostatic and electromagnetic hysteresis effects increase very rapidly with increase in frequency, and difliculty has been experienced in constructing inductors capable of handling large currents of electrical energy at the frequencies corresponding to short electromagnetic Wave lengths. A

The difliculties seem to increase very markedly at frequencies of 1500 kilocycles or higher, the. principal losses at such frequencies occasioned. the generation 1927. Serial No. 187,468.

of heat in the structures which carry the Wire, conducting tube, or' strap employed.

It has been found that the usual insulating materials, such as bakelite, micarta, etc., ha-ve suoli high electrostatic and electromagnetic losses that at the higher frequencies a prohibitive amount of energy is Wastedy in them, causing heating which not infrequently seriously damages the apparatus.

Many of the difficulties hitherto experienced have been solved by the invention covered by application, SerialNo. 5,049, filed in the name of Frank Conrad". As disclosed in that application, an improved inductance device comprises a frame work of Wood which has been carefully dried and covered With a suitable surface-sealing and insulating covering. Upon this Wooden frame Work are mounted a Vplurality 0f insulating members parallel to an axis thereof. These members are preferably formed of molded, heatresisting glass such as pyrex, and are preferably rectangular in shape.

kAccording to the application referred to. these insulator members are provided With a plurality of spaced projections upon one edge adapted to rspace apart the successive turns of a conductor. The insulating members are preferably removably mounted upon the Wooden framework referred to and are held in position by the tension exerted upon the conductor when it is Wound thereon.

Vle have found, however, that in order to provide for a plurality of inductors of Widely differing inductance values, it Was necessary to maintain a very large supply of the insulating pyrex strips referred to. This extra supply necessitates an outlay of money, Which is unduly large.

Ve have also found that the insulator strips did not provide means for readily attaching the, otherwise free ends of the conductor in order to maintain them firmly in position.

Accordingly, by the present invention, We have provided conductor-supporting elements which are readily adapted to be used With inductance devices havin@` Widely differ nt inductance values, and ,lave further se modified the insulating .ps that an end of the conductor may be firmly attached thereto with minimum effort and with assurance that it will not worlr loose. Specifically, our invention. contemplates provid ingl the insulating strips with a plurality of. spaced projections upon each of the edges thereof, the projections on one of the edges being spaced further apart than the projections upon the opposite edge. Each separate pyrex, or glass, strip is thus given a double measure of utility, inasmuch as it may be utilized as a component part in the assembly of inductors having widely different inductance values.

In addition, we have modified the ends of the insulating members by providing notch there`n intermediate of the serrated edges thereof.y The fre-e end of the wire, tube, or strap, may be wrapped around one of the branches of the notch referred to and may be securely anchored in position.

Among the noval features of our invention are those particularly set forth in the appended claim. The invention in its entirety, however, as well as further objects and advantages thereof, will best be understood by reference to the following description of certain specific embodiments taken in connection with the accompanying drawings, in which,

Figure 'l is a side elevational view of an inductance device equipped with a preferred embodiment of our invention,

Figs. 2 and 3 are side and end elevational views, respectively, of a form of our invention adapted 'to support strap, or ribbon, con.- ductors.

Figs. et and 5 are sideand end elevational views, respectively, of a form of invention adapted to support a solid conductor, and

Figs, G and are side and end elevational views', respectively, of a form of our invention particularly adapted to the support of a tube, or pipe, conduct-or having a large diameter.

eiferring to Fig. l, a set of rings l, 2 and 3 have attached thereto a plurality of grooved cross pieces A pair of supporting menibers 5 are respectively attached to the end rings l and I5. As explained in the cepending' application of Conrad previously referred to, all of these nieinliiers are preferably made of wood and are given a special drying and insulatin treatment before assembly.

L plurality of insulating members 6 are mounted in the grooves of the cross pieces 4 and extend parallel to an axis passing through the annular rings. Each of the insiilating members 6 is provided with a plurality of spaced projections 7 upon the edge opposite the edge in Contact with the grooved cross pieces ylfhe edge carrying the projections preferably slightly convex and is provided with rounded corners.

These insulating pieces preferably fit the grooves quite closely in order that the form may be handled without danger, even though the conductor has not been wound around it.

A ribbon, or strap, conductor 8 is wound around the insulating members 6, successive members being shifted axially a slight amount in order to provide for the necessary pitch.

device described is substan- :licaticn referred to. We have prod, however, as before explained, an addiseries spaced projections 9 upon of the members (5 which, in Fig. l, shown in contact with the groovcd cross pieces 4l. These entra` sets of projections are, shown, closer together than the projections which accommodate the strap conductor.

Each end of the insulating members 6 is provided with a notch 1l, having branches l2 and i3, which provides means for securely anchoring the ends of the conductor shown in Figs. 3, 5 and 7.

By winding a flat conductor having a width equal to the space between the projections, successively around the insulating members until all of the spaces have been occupied and the wire securely anchored, an inductor may be provided having an accurately predetermined inductance value. If, for any reason, it is desired to change the inductance value, the conductor may be removed, all of the insulating members reversed, and a second conductor having a width equal to the spaces between the projections now uppermost may be wound around the elements and anchored in the manner just described. It is also possible to accurately predctermine, within a small percentage of error, the inductance value of thesecond inductor.

The principal advantage of our in ventiou lies in the fact that a large number of differing inductance devices may be constructed by utilizing the same fixed wooden form and by making use of but a small number of differing insulating strips. lVhen the insulating strips are constructed according to our invention it is possible to reduce the replacement stock of insulators necessary to be kept on hand by 50%, at least, if not more.

The provision of the anchoring notch 1l permits the inductor to be assembled much more rigidly than if the ends of the conductor are merely wrapped around the unnotched ends of the insulator strips, as shown in the Conrad application previously referred to.

Although we have shown but three embodiments of our invention in the accomjanying drawings, many modifications thereof will be apparent to those skilled in the art. Our invention, therefore, to be limited only by the prior art and by the spirit of the appended claim.

We cla-im as our invention:

A coil supporting device comprising a frame, and a plurality of elongated approximately rectangular insulating elements removably supported thereby in circumferential spaced relation, an exposed edge of each of said elements being provided with a series of convolution-separating projections, an- 'other edge of each of said elements being provided with a plurality of convolution-separating projections dilierently spaced from the projections on said exposed edge, whereby upon reversal of said elements relative to said frame a conductor may be Wound about said elements to constitute a coil having a value oi" inductance different from that of a. coil formed bv Winding an inductor around said elements before their reversal.

In testimony whereof, We have hereunto 2o subscribed our names this 25th day of April,

ROBERT L. DAVIS. JOHN P. STAKEL. 

